Gary G Mittelbach

Michigan State University | MSU · Department of Integrative Biology

Community Ecology provides a broad, up-to-date coverage of ecological concepts at the community level and is suitable for advanced undergraduates, graduate students, and ecological researchers. The field of community ecology has undergone a transformation in recent years, from a discipline largely focused on processes occurring within a local area...

This chapter uses simple theory and experiments to address the fundamental question of what determines the biomass (abundance) of different trophic levels (plants, herbivores, carnivores) in a community. Theory predicts joint control of trophic-level abundance by bottom-up effects (resources) and top-down effects (predation), with the relative stre...

This chapter introduces the field of community ecology and reviews its history. The first community ecologists were botanists who noted what appeared to be repeated associations between plant species along environmental gradients. From these studies arose the concept of ecological succession. Laboratory and field studies of animal populations gener...

This chapter explores ecological networks and their properties. Ecological networks summarize the many potential interactions between species within a community by representing species as nodes in the network and using links between nodes to represent the interactions between species. The earliest and best-studied ecological networks are food webs...

Ecologists have long puzzled over the question of how multiple species may coexist in a community in the face of strong interspecific competition. This chapter explores the answers that modern coexistence theory provides to this question. Spatial and temporal heterogeneity in the environment, in conjunction with species differences in resource use...

This chapter reviews the basic mathematics of population growth as described by the exponential growth model and the logistic growth model. These simple models of population growth provide a foundation for the development of more complex models of species interactions covered in later chapters on predation, competition, and mutualism. The second ha...

Ecology and evolution go hand in hand. However, since evolution occurs over relatively long time scales, ecologists had long thought it unlikely that evolutionary events could affect population dynamics or species interactions in ecological time. This view is changing. Today, there are multiple areas of research examining how evolutionary processes...

This chapter examines the relationship between biodiversity (most often measured as species richness) and the functioning of ecosystems. Examined in detail are the effects of biodiversity on: ecosystem productivity, nutrient use and nutrient retention, community and ecosystem stability, and invasibility by exotic species. A careful look, over two d...

Just as the dispersal of individuals may link the dynamics of populations in space, the dispersal of species among communities may link local communities into a metacommunity. Four different perspectives characterize how dispersal rates, environmental heterogeneity, and species traits interact to influence diversity in metacommunities. These perspe...

Predators feed on a variety of prey and this has important consequences for both predator and prey. This chapter introduces optimal foraging theory as a way to understand why predators prefer some prey types over others and discusses the evidence for adaptive diet choice in nature. Simple optimality models are used to understand how predators make...

There is perhaps no more fundamental question in ecology than what determines the number and kinds of species found in a community and their relative abundances. This chapter lays out a powerful approach to answering this question, based on the concepts of a regional species pool and environmental filters. The species pool is the set of species tha...

Populations and species are distributed heterogeneously across the landscape and this has important consequences for their abundance, persistence, and interactions with other species. This chapter introduces the concept of a metapopulation, a “population of populations”, where populations occur in patches of suitable habitat surrounded by areas of...

The consequences of beneficial interactions for the diversity and functioning of communities remain poorly understood, but this is changing. This chapter examines how mutualism may evolve in the face of cheating, using the concept of biological markets where members of each species exchange resources and services, with associated costs and benefits...

Species and communities may exist in a dynamic state of change in response to environmental variation and disturbance. This chapter explores the consequences of variable environments and disturbance to species interactions and community structure. In particular, it examines how disturbance can result in the succession of ecological communities, how...

This chapter reflects on the successes achieved and challenges that remain in the study of ecological communities. It concludes with a discussion of research topics expected to occupy the attention of community ecologists for the next decade or so and that may yield big dividends in terms of understanding the processes that structure communities an...

This chapter examines how biodiversity, the variety of life, is distributed across the globe and within local communities. It begins by considering some of the challenges associated with assessing biological diversity at different spatial scales. Then, three of the best-studied patterns in species richness are examined in detail—the species–area re...

Interspecific competition is a major factor influencing the structure of communities. This chapter examines the principles of interspecific completion, defined as a reduction in the population growth rate of one species due to presence of one (or more) other species due to their shared use of limiting resources or active interference. The chapter b...

This chapter introduces the concept of the consumer-resource link, the idea that each species in a community consumes resources and is itself consumed by other species. The consumer–resource link is the fundamental building block from which more-complex food chains and food webs are constructed. The chapter continues by exploring what is arguably t...

Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised...

Fertilization of grasslands commonly leads to species loss and a dramatic shift in species composition, but the mechanisms underlying this pattern remain unclear. One oft-stated hypothesis is that fertilization increases competition for light and/or reduces spatial heterogeneity of resources, thereby reducing the niche dimensionality for species to...

The nearly universal pattern that species richness increases from the poles to the equator (the latitudinal diversity gradient [LDG]) has been of intense interest since its discovery by early natural-history explorers. Among the many hypotheses proposed to explain the LDG, latitudinal variation in (1) productivity, (2) time and area available for d...

To date,most studies investigating the relationship between personality traits and fitness have focused on a single measure of fitness (such as survival) at a specific life stage. However, many personality traits likely have multiple effects on fitness, potentially operating across different functional contexts and stages of development. Here, we a...

Dispersal rates play a critical role in metacommunity dynamics, yet few studies have attempted to characterize dispersal rates for the majority of species in any natural community. Here we evaluate the relationship between the abundances of 179 plankton taxa in a pond metacommunity and their dispersal rates. We find the expected positive relationsh...

Online enhancements: appendix. Dryad data: http://dx.doi.org/10.5061/dryad.70sr1. abstract: The nearly universal pattern that species richness increases from the poles to the equator (the latitudinal diversity gradient [LDG]) has been of intense interest since its discovery by early natural-history explorers. Among the many hypotheses proposed to e...

The nearly universal pattern that species richness increases from the poles to the equator (the latitudinal diversity gradient, LDG), has been of intense interest since its discovery by early natural-history explorers. Among the many hypotheses proposed to explain the LDG, latitudinal variation in 1) productivity, 2) time and area available for div...

Plant–herbivore interactions occur in all ecosystems and provide a major avenue for energy flow to higher trophic levels. A long-standing hypothesis to explain the latitudinal gradient in species diversity proposes that the relatively stable and frost-free climate of the tropics should lead to more intense biotic interactions in tropical compared w...

Ecologists often view community assembly as a process involving the dispersal of species from a static regional species pool followed by environmental filtering to establish the local community. This conceptual framework ignores the dynamic nature of species pools and fails to recognize that communities are assembled by processes operating over a v...

Fertilization via agricultural inputs and nutrient deposition is one of the major threats to global terrestrial plant richness, yet we still do not fully understand the mechanisms by which fertilization decreases plant richness. Tall clonal species have recently been proposed to cause declines in plant species richness by increasing in abundance in...

Fish have proven to be model organisms for the study of animal personalities, and a rich literature documents consistent interindividual behavioral differences in a variety of species. However, relatively few studies have examined the ecological consequences of such consistent interindividual differences in behaviors in fish or other organisms, esp...

Background/Question/Methods Community ecology’s turbulent history includes a number of “near-death” experiences, one of which (the great null-model debate) coincided with the publication of Robert McIntosh’s book on The Background of Ecology: Concept and Theory in 1985. The years since McIntosh’s book have witnessed many more ups and down in the m...

Background/Question/Methods Nutrient pollution and fertilization are ubiquitous worldwide and lead to declines in plant species richness. However, the role of particular plant functional traits in determining which species benefit and which species are harmed in response to fertilization remains an open question. In a 10-year field experiment, we...

Background/Question/Methods Previous theoretical work suggests that nutrient recycling through plant litter may allow plants with a larger foraging footprint to facilitate smaller plants, promoting coexistence of the two strategies. Separate smaller ’patches’ within a large plant’s foraging footprint may differ in the relative rates at which differ...

Decreases in plant species richness and shifts in community structure following fertilization are usually attributed to increasing light limitation. However, there is increasing evidence that light limitation alone does not account for all of the observed effects of fertilization on plant communities. We present a model of competition for a single,...

Our planet shows striking gradients in the species richness of plants and animals, from high biodiversity in the tropics to low biodiversity in polar and high-mountain regions. Recently, similar patterns have been described for some groups of microorganisms, but the large-scale biogeographical distribution of freshwater phytoplankton diversity is s...

Spatial heterogeneity in soil resources is widely thought to promote plant species coexistence, and this mechanism figures prominently in resource-ratio models of competition. However, most experimental studies have found that nutrient enhancements depress diversity regardless of whether nutrients are uniformly or heterogeneously applied. This mism...

While crayfish are traditionally considered fish prey, they are capable of feeding on substrate-bound fish eggs and their introductions have been blamed for the decline in fish populations in Europe and North America. To investigate their potential effects on fish reproductive success we measured the effects of a native crayfish (Orconectes virilis...

Diel migrations of the golden shiner (Notemigonus crysoleucas) from the littoral to limnetic zone of a small Michigan lake were documented through visual observations and gill netting. During the day golden shiners schooled in the littoral zone. Just after sunset schools broke up and the golden shiner migrated to the open water regions of the lake....

The size distributions of invertebrate prey found in the vegetation, bare sediment, and open water habitats of a small, Michigan lake were quantified for the months of May through August, 1979. The distribution of prey body size in each habitat generally conformed to a lognormal distribution, allowing a simple characterization of prey size and abun...

We introduce nutrient recycling into a model where competitors differ in the scale at which they perceive their environment. In a two-resource system with both external nutrient inputs and recycling, larger consumers ("integrators") often generate resource distributions that favor their smaller ("nonintegrator") competitors, and vice versa. This oc...

Background/Question/Methods A tradeoff between increased foraging activity and predation risk may maintain behavioral variation within a population. However, little is known about whether individual behaviors are consistent or if individuals show plasticity in various contexts. We used bluegill sunfish (Lepomis machrochirus) to test whether exposur...

Background/Question/Methods A latitudinal gradient in species richness is the Earth’s predominant biodiversity pattern, yet how and why this gradient arose remains unresolved. Biotic interactions play a key role in many of the hypotheses that have been put forward to explain the latitudinal diversity gradient (LDG). In my introductory talk to the...

Background/Question/Methods Recently, ecologists have found that a tradeoff between increased foraging activity and predation risk may lead to behavioral variation within a population, with individuals showing consistent, repeatable responses to foraging tradeoffs. Most of the work on this subject has been conducted in the laboratory, where behavi...

Background/Question/Methods The link between environmental heterogeneity and opportunities for species coexistence is well established theoretically, but has received mixed experimental support. Understanding the causes of the discrepancy between theoretical and empirical results is an important goal. For example, we found that in a long-term exper...

Background/Question/Methods Spatial heterogeneity in soil resources is thought to promote the coexistence of plant species, with a critical factor being the scale of resource heterogeneity relative to plant size. We hypothesized that clonal species, by integrating across patches, may experience patch sizes differently than non-clonal species and t...

Biotic interactions are believed to play a role in the origin and maintenance of species diversity, and multiple hypotheses link the latitudinal diversity gradient to a presumed gradient in the importance of biotic interactions. Here we address whether biotic interactions are more important at low latitudes, finding support for this hypothesis from...

In a growing body of literature from a variety of ecosystems is strong evidence that various components of biodiversity have significant impacts on ecosystem functioning. However, much of this evidence comes from short-term, small-scale experiments in which communities are synthesized from relatively small species pools and conditions are highly co...

Aim We surveyed the empirical literature to determine how well six diversity hypotheses account for spatial patterns in species richness across varying scales of grain and extent. Location Worldwide. Methods We identified 393 analyses (‘cases’) in 297 publications meeting our criteria. These criteria included the requirement that more than one dive...

Environmental perturbations (e.g., disturbance, fertilization) commonly shift communities to a new mean state, but much less is known about their effects on the variability (dispersion) of communities around the mean, particularly when perturbations are combined. Community dispersion may increase or decrease (representing a divergence or convergenc...

Variation in the intensity of predation across the well-known environmental gradient of freshwater habitats from small, ephemeral ponds to large, permanent lakes is a key factor in the development and maintenance of aquatic community structure. Here, we present data on the distribution and abundance of four species of Chaoborus (Diptera: Chaoborida...

Clonal plants that are physiologically integrated might perceive and interact with their environment at a coarser resolution than smaller, non-clonal competitors. We develop models to explore the implications of such scale asymmetries when species compete for multiple depletable resources that are heterogeneously distributed in space across two pat...

While the number of studies investigating the effects of species diversity on ecosystem properties continues to expand, few have explicitly examined how ecosystem functioning depends quantitatively on the degree of niche complementarity among species. We report the results of a microcosm experiment where similarity in habitat use among aquatic snai...

1. Coexistence theory predicts that greater heterogeneity of resources or other fitness constraining environmental factors will promote species diversity, yet this classic mechanism of coexistence has rarely been tested in manipulative field experiments. 2. Here we present results from the fourth year of a long-term experiment designed to test the...

A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. The time and area hypothesis holds that tropical climates are older and historically larger, allowing more opport...

Question: Can we develop simple allometric relationships based on predator and prey body size to more easily parameterize optimal foraging models and thereby make them more useful to community ecologists interested in studying species interactions? Model: The rate at which a predator encounters its prey is often the most difficult parameter to esti...

Whether communities respond smoothly or discontinuously to changing environmental conditions has important consequences for the preservation and restoration of ecosystems. Theory shows that communities may exhibit a variety of responses to environmental change, including abrupt transitions due to the existence of alternate states. However, there ha...

The relationship between species diversity and the stability and production of trophic levels continues to receive intense scientific interest. Though facilitation is commonly cited as an essential underlying mechanism, few studies have provided evidence of the impact that indirect facilitation may have on diversity–ecosystem functioning relationsh...

The diversity and composition of a community are determined by a combination of local and regional processes. We conducted a field experiment to examine the impact of resource manipulations and seed addition on the invasibility and diversity of a low-productivity grassland. We manipulated resource levels both by a disturbance treatment that reduced...

Broad-scale variation in taxonomic richness is strongly correlated with climate. Many mechanisms have been hypothesized to explain these patterns; however, testable predictions that would distinguish among them have rarely been derived. Here, we examine several prominent hypotheses for climate–richness relationships, deriving and testing prediction...

Mortality (e.g. predation, disturbance) is often thought to lower the intensity of interspecific competition and thereby promote the coexistence of competing species. However, surprisingly few tests of this idea exist, especially for metazoans feeding on a self-renewing resource. Here we examined the effect of density-independent mortality on the c...

In 2001, Simon Levin remarked at a National Science Foundation meeting on biocomplexity that scientific disciplines are belief systems that progressively nurture memes by establishment of societies and journals (a meme being a unit of intellectual or cultural information—a key idea—that passes from mind to mind, spreading through colleagues and ove...

Experiments and theory in single trophic level systems dominate biodiversity and ecosystem functioning research and recent debates. All natural ecosystems contain communities with multiple trophic levels, however, and this can have important effects on ecosystem structure and functioning. Furthermore, many experiments compare assembled communities,...

It is often claimed that we do not understand the forces driving the global diversity gradient. However, an extensive literature suggests that contemporary climate constrains terrestrial taxonomic richness over broad geographic extents. Here, we review the empirical literature to examine the nature and form of the relationship between climate and r...

A new analysis of the nearly century-old Lotka–Volterra theory allows us to link species interactions to biodiversity patterns, including: species abundance distributions, estimates of total community size, patterns of community invasibility, and predicted responses to disturbance. Based on a few restrictive assumptions about species interactions,...

Flexible behavior has been shown to have substantial effects on population dynamics in unstructured models. We investigate the influence of flexible behavior on the dynamics of a size-structured population using a physiologically structured modeling approach. Individuals of the size-structured population have a choice between living in a risky but...

Adult fish may affect the growth and survival of conspecific larvae through a variety of pathways, including negative interactions via competition for shared limiting resources or via predation (i.e., cannibalism), and positive interactions due to the consumption of larval predators and via resource enhancement (i.e., presence of adults increases a...

Understanding the relationship between species richness & productivity is fundamental to the management & preservation of biodiversity. Yet despite years of study & intense theoretical interest, this relationship remains controversial. Here, we present the results of a literature survey in which we examined the relationship between betweens species...

A key issue in ecology is how patterns of species diversity differ as a function of scale. The scaling function is the species-area curve. The form of the species-area curve results from patterns of environmental heterogeneity and species dispersal, and may be system-specific. A central concern is how, for a given set of species, the species-area c...

Pumpkinseed (Lepomis gibbosus) and redear sunfish (L. microlophus) are sister species with largely allopatric native ranges. For purposes of sport fishery enhancement, redear have been introduced into lakes of southern Michigan, and as a result, a large zone of artificial sympatry of pumpkinseed and redear has been created. Redear and, to a lesser...

Crayfish are a major constituent of benthic invertebrate production in both lentic and lotic habitats. Crayfish also provide an important food resource for many fish. Because of their abundance and relatively large body size, the interactions between fish and crayfish can have profound effects on the rest of the benthic community. In this paper we...

Recent overviews have suggested that the relationship between species richness and productivity (rate of conversion of resources to biomass per unit area per unit time) is unimodal (hump-shaped). Most agree that productivity affects species richness at large scales, but unanimity is less regarding underlying mechanisms. Recent studies have examined...

1. Bluegill sunfish (Lepomis macrochirus) dominate fish assemblages of small lakes and ponds throughout the eastern United States and may play a major role in structuring aquatic communities. We examined the impact of adult bluegill on amphibian density by stocking bluegill at a range of densities into partitions of an experimental pond in which am...

Pumpkinseed sunfish exhibit considerable intraspecific variation in jaw morphology, with population-level diVerences in the size of key morphological structures often exceeding 200%.

Pumpkinseed sunfish exhibit considerable intraspecific variation in jaw morphology, with population-level differences in the size of key morphological structures often exceeding 200%. This inter-population variation is correlated with differences in the availability of gastropods, the pumpkinseed's primary prey. Such resource polymorphisms may be a...

In this study, we review the wealth of ecological information available for 27 species of freshwater piscivores from Europe and North America and examine the factors that determine variation in the diet ontogeny of piscivores and consider some of the ecological consequences of this variation. Focusing on interspecific variation, we found that speci...

Consider the following questions: 1) If we manipulate one species in a food web will this change the population of a species that neither eat nor are eaten by the manipulated species? 2) If removing species A in food web 1 causes a 20% in species B, can we assume that a similar decrease of B will occur if we remove species A in web 2, which contai...

Over 30 years ago, Hairston et al. (1960) published a short, insightful, and controversial paper (see also Slobodkin et al. (1967)) that attempted to explain how resource limitation and predator limitation varied among different trophic levels. Hairston et al. restricted their arguments to terrestrial systems with three trophic levels; however, Fre...

This paper presents the results of a long-term study of changing predator densities and cascading effects in a Michigan lake in which the top carnivore, the largemouth bass (Micropterus salmoides), was eliminated in 1978 and then reintroduced in 1986. The elimination of the bass was followed by a dramatic increase in the density of planktivorous fi...

In predator-prey interactions between size-structured populations, small (young) predators may compete with species that ultimately become their prey. We tested experimentally whether such competition occurs between young-of-year (YOY) largemouth bass and their eventual prey, bluegill. In a divided experimental pond, target densities of YOY bass an...

Foraging theory provides a potentially powerful tool for understanding the interaction between a predator population and its prey assemblage. We illustrate how foraging models developed for the bluegill (Lepomis macrochiros Rafinesque) and pumpkinseed sunfish (L gibbosus (Linnaeus)) can be used to translate measures of prey size and abundance into...